Incandescent electric lamp.



J. A. ORANGE.

INCANDESCENT ELECTRIC LAMP.

APPLICATION FILED ARR. 19. 1913.

Witnesses Inventor-1 %4 John Orange 5 /7 His fittor-ne g.

UN TED STATES PATENT oEEIoE.

JOHN ARTHUR ORANGE, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.-

INCANDESCEN T ELECTRIC LAMP.

Specification of Letters Patent.

Patented July 4, 1916.

To all whom it may concern:

Be it known that I, JOHN ARTHUR ORANGE, a subject of the King of Great Britain, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Incandescent Electric Lamps, of which the following is a specification.

My present invention relates to incandescent lamps, and more especially to improvements in that type of lamp in which the bulb of the lamp contains a considerable pressure of some, inert gas such as nitrogen. It has been found that a very material increase in efficiency may be-obtained in lamps having high melting point filaments, such as those of tungsten, provided the filament be of relatively large diameter, or wound in concentrated form to give the eflect of large diameter, and be operated at an excessively high temperature and under conditions which serve to reduce the amount of vaporization' 0r wasting away of the filament.

This wasting away of the filament is reduced by operating the filament in an atmosphere,

for example, of nitrogen free from water of; the filament.

and of considerable pressureamounting say to that corresponding to 20 inches of mercury pressure or higher. In order that the proportion of energy lost by heat conduction into the gas' may be made as small as possible, the filament is made of relatively large diameter, for the reason that it has been found that within fairly wide limits, the amount of heat lost by conduction .is substantially the same, though the. amount of light radiated is proportional to the surface limits the higher the efficiency.

In order to secure an efiiciency of operation' of a tungsten or' similar filament higher than is possible when operated in a vacuum-namely, about one watt per candle power lighting efliciencyit is necessary to run the filament at a higher temperature 2 than in a vacuum, and in fact at such an excessively high temperature so that the gain in-light emission more than. balances the increased heat loss by conduction of heat from the filament into the surrounding gas. The of gas arising from such convection currents an excessively hot filament, are accompanied by excessively high temperatures of the gas:v

so that if the gas at this high temperature Other things being equaltherefore, the larger the filament, Within parts of the bulb, water vapor and other gases are apt to be driven out of the glass.

The presence of watervapor especially is very detrimental and leads to blackening of the bulb. To avoid this diificulty I mount the filament at the ends of long supporting leads of refractory metal such as tungsten, so that the hot gases rising from the filament do not immediately come .in contact with the glass parts of the bulb but have an opportunity to cool as they rise, whereby when the gases do come in contact with the glass parts of the bulb no deleterious effect results.

In the accompanying drawings, I have represented a lamp embodying my invention. In this case the bulb of the lamp is indicated at l. The filament inthis case of tungsten is indicated at 2, and is, for example, 10 mils in diameter, and say 2% inches long or more.

from long heavy wires or leads 3 of tungsten or molybdenum, serving to carry current to the filament and connected to leading-in conductors 4. These leading-in conductors 4 pass through the usual glass seal 5. It will be observed that by supporting the filament 2 from the lower ends of the rods 3, the filament is thus considerably removed The filament is supported from the vicinity of the seal 5 and adjacent parts. The upper portion of the lamp bulb therefore in a measure becomes a sort of 1 of the bulb, the,

lamp bulb, a filling of gas therein of at least about 20 inches of mercury pressure, a filament of refractory metal therein operable in said gas at a temperature substantially higher than the temperature corresponding in a vacuum to one watt per candle power lighting efficiency, and long bare metallic lead wires for said filament, the said lead wires being located in said bulb in the path of gas convection currents and supporting said filament far enough away from the glass parts of the lamp to permit convection currents of heated gas to cool substantially before coming into contact with said glass parts.

2. An incandescent lamp comprising an elongated bulb, a filament of tungsten located near one end of said bulb, a gas inert with respect to tungsten at incandescence and of at least about 20 inches of mercury pressure, and long bare lead wires of refractory metal for said filament extending upwardly away from said filament in the 5 operating positionoof the lamp, and sealed into the bulb remote from the filament, the portion of the bulb surrounding the lead wires constituting a depositing chamber for vaporized filament material.

In witness whereof, I have hereunto set my hand this 17th day of April, 1913.

JOHN ARTHUR ORANGE. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD. 

